ES2344742T3 - METHOD AND APPLIANCE FOR CONFORMING A PRESSURE STEEL CONTAINER, SUCH PRESSURE STEEL CONTAINER AND A PREFORM OF THE SAME. - Google Patents

Abstract

The invention relates to a method for forming a steel container (1) having a curled open end, comprising the steps of: i) providing a steel cup (11); ii) deep drawing the steel cup (11) into a drawn container preform (12); iii) thin drawing the body of the drawn container preform (12); and iv) curling an open end of the drawn container preform by forming a precurl (16) and by curling the precurl (16) into an elongated curl (19), to a apparatus for forming a steel container (1), and to such steel container (1) and its preform.

Description

Method and apparatus for forming a container of pressure steel, said pressure steel vessel and a preform of the same.

The present invention relates to a method and an apparatus for forming a steel container, to said container  of steel and a steel container preform therefore and also to a container provided at its open end with a unit of dispensing or closing.

These containers can be used as pressure vessel, for example for aerosol distribution,  food products such as dressings, gas mixtures with Sweet smell and the like. The pressure in said pressure vessel It can vary from 1 to 30 bar, in particular, from 10 to 20 bar. These Pressure vessels are usually made of aluminum.

Currently, there is a tendency to use Steel instead of aluminum. The production of containers made of Steel is problematic. For reasons that the container is going to make starting from a steel cup or sheet steel. The Steel cup will be shaped into a container preform and it will be will provide a flange and, optionally, a free end with neck shape in which the flange is formed. On this flange a closure or dispensing unit is to be seized. All these manipulations that start from sheet steel or a cup steel need the metal to be suitable to be subjected to operations that conformation that cause a thinning of the steel cup wall and additional radial expansion and the diameter reduction during beading and / or neck formation

US 4,711,611 refers to a method and an apparatus for manufacturing a can body. Starting to starting from an initial piece and using a method known as method of "inlay-stretched-ironed" or "embedded-re-embedded" method conforms a container. In order to avoid the appearance of lugs on the edge upper can body finished the initial piece is selected appropriately with respect to the grains of the material. After stuff the body, the body is ironed and the upper edge of the cylindrical wall formed is trimmed in order to provide a uniform edge. To this the container preform is subjected to the action of a trimming roller that moves over the surface and around the circumference of the free end of the container. This results in residual stresses that extend in the direction Tangential and in a spiral direction. This results in the free end spiraling. In addition this cut will lead to the formation of sharp steel fragments at the free end trimmed or sharp independent steel fragments that can injure the user of the method and the device.

The present invention aims at provide a method for the formation of a steel vessel, such as a pressure vessel, said vessel complies with the requirements for the container and the container preform in relation to the formation at low variations of dimensions, failure of steel material or forming tools, and finally to the requirements that steel vessels must be produced at a reasonable speed, such as 500-2000 steel containers per minute.

According to a first aspect of the present invention a method for the formation of a container of steel, such as a pressure vessel, which has an end open with flange according to claim 1.

The method according to the invention comprises two critical shaping operations that are a deep drawing  and the subsequent fine drawing. In the drawing operation deep the container preform conforms to an increase in the cup height, decreasing cup diameter and thickness decreasing body The container preform formed after Deep drawing is not suitable for an operation rear flange where the open end is beaded of the inlay container. The steel material fails due to the formation of cracks and irregular ridges with great variation of flange dimensions. However, if the preform of deep drawing container is first stuffed fine before beading, then the problems of Beaded described above. The invention is based on the appreciation that after deep drawing the body of the embedded container preform does not have the same thickness of material along the preform body height of inlay container. Starting from the bottom of the preform of inlay container the thickness of the body wall increases towards The open end. If the fine drawing reduces the body wall thickness at least at the open end (which will be subjected to the beading operation) and a substantially constant wall thickness, then beading of this open end subjected to fine drawing results in Good quality flanges.

According to the preferred embodiment the steel cup used in deep drawing operation is formed from of the steel sheet preferably by deep drawing.

This deep drawing operation is performed preferably in several stages of deep drawing. During these stages of deep drawing the wall diameter of the body gradually decreases while at the same time the Cup height is gradually increased. The body of the cup it can have a thickness equal or slightly reduced with respect to the Original steel sheet from which the steel cup is formed. Depending on the dimensions of the container preform stuffed the number of deep drawing stages is approximately 2-6 deep drawing stages such as 3 stages of deep drawing.

Usually a container is provided with a concave bottom that increases the strength of the particular container at (higher) pressures that may result from the use of containers that have a thinner bottom (therefore starting from a thinner steel plate). The concave bottom can be formed in the container preform during or after the operation of deep drawing The embedded container preform has a irregular free edge that can interfere with subsequent shaping operations This irregular free end is Remove by trimming by tightening.

The embedded container preform having been subjected to deep drawing and fine drawing of the body now could now undergo the beading operation during the that a first first flange is formed and then the flange previous conforms to an elongated flange. The flange must have substantially constant dimensions for reasons that in this flange is going to grab the closure or the dispensing unit with what that a seal will be formed.

According to a preferred embodiment a free end zone of the embedded container preform is subject to the formation of a neck so that the formed flange subsequently resides inside an imaginary body wrap of container In other words, the outer diameter of the flange It is smaller than the diameter of the container body according with the invention The free end zone is subjected to a neck forming operation preferably in the form of several stages of neck formation that could add up to 2-10 stages of neck formation, such as 7-3 stages of neck formation, such as 5 or 6 stages of neck formation. Neck formation through that the diameter is reduced requires an inward movement of the material of the end zone. In order to control as much as this movement is possible inside the end zone during your neck formation it is preferable that at least one neck training stage comprise a training stage of collar with chuck During the formation of neck with mandrel the part of the end zone subjected to the operation of forming neck comes into contact with the mandrel and, resting on the mandrel inserted, pushed or stuffed through a formation ring of neck. This results in a more neck training operation reliable and to a neck part with less diameter variation and thickness and a low number of faults. When the free end with neck shape is going to be trimmed means can be used Classic cutting swivel. However, it is preferred to trim by trimming by tightening by using a mandrel of Trimming by additional or adapted tightening.

According to a preferred embodiment the Steel used for shaping the steel vessel is coated on at least one side of a coating. Saying coating can be a coating to prevent corrosion of steel or improve its quality, reduce friction or provide A good aesthetic appearance. An example of such a coating It is the PET. The steel can be coated on one side or both faces and if it is coated on both sides the coating can have a different thickness. The inside of the container may have a thicker coating than the exterior coating. He coating may have a thickness of 10 to 100 micrometers, such such as 15 to 40 micrometers, in particular 20 to 30 micrometers. For example, the thickness of the coating on the inner face of the container can be 30 micrometers and outside 20 micrometers

During deep drawing, drawing fine, neck and beading training operations the forces with which the coating is coated and adheres on the steel may be insufficient to be subjected to these operations or a rough outer surface would occur. For overcome these inconveniences, it is preferable to submit the coating to a heating operation, such as a heating at 100-400 ° C, preferably 150-350 ° C, such as 200-300 ° C. These temperatures to be applied must be determined by routine experimentation in relation to the material of the coating and its thickness. For PET a heat treatment to 280 ° C is sufficient to improve the adhesion to the surface of steel. The heating is preferably carried out by induction heating, which allows local heating in particular of the part of the container that is being subject to the neck and beading formation. This treatment of Preferred heating comprises induction heating. He induction heating has another important advantage that is that you don't need to establish contact between an item heater and preform to heat. If necessary you can apply a heating operation adapted to the concave bottom covered.

Another aspect of the invention relates to a apparatus for forming a steel container according to the claim 1.

The apparatus preferably comprises a unit for the conformation of a steel cup, when the steel cup It is going to be made of sheet steel.

In relation to the drawing apparatus deep to be performed, the apparatus comprises a unit of deep drawing that has several subunits of drawing deep in order to carry out the following stages of deep drawing The number of deep drawing subunits preferably add 2 to 6, such as 3 subunits of deep drawing

According to a preferred embodiment the apparatus comprises a unit for shaping a bottom concave in the embedded preform container.

If the container preform is to be trimmed by tightening at its free end then the device according to the The invention comprises a clamping unit.

If the steel container according to the invention is going to be provided with a neck-shaped end zone then the apparatus according to the invention comprises a unit of neck formation to shape an end zone neck free of the embedded container preform, comprising preferably several neck forming subunits, such as 2-10 subunits of neck formation. With the final purpose of carrying out the neck training unit by mandrel neck formation then the apparatus comprises a (sub) neck forming unit with mandrel. As mentioned previously, you can use a trimming unit (for tighten) to trim the free end with the shape of a neck.

For a preferred heating of the area of free end that will be shaped like a preform neck of steel container, the apparatus is provided with a unit of heating which is preferably a heating unit inductively.

The characteristics and features mentioned and others of the method and apparatus for forming a steel container will be clarified further in the following description of several embodiments, said description is provided for purposes illustrative and not intended to limit in any way the method and apparatus according to the invention. In the description it will be done reference to the drawings in which

Figure 1A shows a perspective view of a steel container according to the invention;

Figure 1B shows in cross section this steel container provided with a dispensing unit;

Figure 2 is a schematic flow chart of the method according to the present invention that produces two containers different steel;

Figures 3A-3C show in cross section and schematically drawing operation deep starting from sheet steel;

Figure 4 shows a perspective view of enlarged scale of the steel cup formed in Figure 3C;

Figures 5A-5C show a second deep drawing operation;

Figure 6 shows in perspective a view of the embedded container preform formed in Figure 5C;

Figures 7A-7D show a third stage of deep drawing including bottom formation concave vessel;

Figure 8 shows in perspective a view of the embedded container preform formed in Figure 7D;

Figures 9A-9C show of illustrative manner the free end heat treatment of body of an embedded container preform according to the invention;

Figures 10A-10C show the fine drawing stage of the container preform body inlay and free edge trimming;

Figures 11 and 12 show the release and a perspective view of the submitted steel container preform to deep drawing, fine drawing and trimming;

Figures 13-13D show in cross section and schematic a first training operation neck through neck formation with mandrel;

Figures 14A and 14B show an operation posterior neck formation with mandrel;

Figures 15 and 16 illustrate the operation of cut after neck formation and container preform  conformed with neck;

Figures 17 and 18 show the apparatus and various stages of the formation of the previous flange;

Figures 19A-19C show the second beading operation with pre-flange beading up to an elongated flange;

Figures 22-25 show another preferred embodiment of the fine drawing operation which includes trimming by tightening

Figure 26 is detail XXVI of the figure twenty-one;

Figure 27 is an enlarged detail XXVII of the technique of figure 22;

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Figure 28 shows in an alternative to tightening operation during a last operation of neck formation, and

Figure 29 is a XXIX scale detail enlarged in figure 28.

Figure 1A shows a container, for example a pressure vessel 1, made of steel according to the invention. The container 1 comprises a body 2, an area of free end 3 with neck shape and elongated flange 4.

Figure 1B shows the container 1 according with the invention in the form of an end product 5 since the end Open 6 of container 1 is closed by a unit 7 dispenser held on top. Figure 18 also shows the concave bottom 8.

Figure 2 shows the different stages of the method according to the invention for forming a container of steel 1 or 9. A steel plate 10 is subjected to deep drawing until forming a cup 11 and then a preform 12. The posterior preform 13 deep drawing is trimmed at the edge free and a concave fund is provided 18. After a first This preform 14 is provided with a pre-flange 16 in its free end zone and, finally, an elongated flange 19 to form the container 9.

According to another embodiment the area of free end has a neck shape which forms part 17 with neck shape, which is subsequently provided with a previous flange 18 and an elongated flange 19 to form the container 1.

Figures 3-8 show with detail the deep drawing operation for shaping an inlay container preform.

Figure 3A shows a first operation of deep drawing in which the steel plate 10 is formed in a cup 11. The steel plate 10 in the form of a circular disk is place in a first deep drawing tool 20 cooperating with a drawing tool 21, provided with a forming cavity 22 in which the tool 20 is pressed Deep drawing. The formed cup 11 has a diameter of 33 mm and a cup height of 32 mm (see figure 4).

Figure 5 shows a second operation of deep drawing using a drawing tool 23 deep cooperating with another deep drawing tool 24 provided with a cavity 25 in which the tool 23 is seen forced to thereby form container preform 12 with a cup diameter of 27 mm and a cup height of 55 mm (see figure 6).

Figure 7 shows a third operation of deep drawing in which the preform 12 of figure 6 is placed on a deep drawing tool 26, which cooperates with a deep drawing tool 27, which is provided with a bottom shaping tool 28. In figure 7B you produces deep drawing of the body of the preform 12 until that in figure 7C the preform is pressed against the tool 28 to form the concave bottom. Figure 7D shows the release of preform 30 provided with the concave bottom 8. As shown in figure 8 this preform 30 has an edge 31. This preform 30 It has a cup diameter of 22 mm and a cup height of 66 mm

Figure 9 shows an operation of heating to which the preform 30 or 13 can be subjected in its free end zone 32. Due to induction heating the heated preform 33 acquires a bright end zone 34 and a bottom area without brightness 35 due to this heat treatment of the steel coating improves the forces in which the coating adheres to steel. It should be noted that this stage of heating can also be carried out after fine drawing of the preform as explained in relation to the Figures 10 to 12. If the preform is provided with a concave bottom, then it is preferable to heat the bottom part (80-120 ° C for 20-60 seconds) to avoid cracking by stretching.

As noted earlier in this report the preform obtained in the third deep drawing operation, as explained in figure 7, it has a wall thickness near its bottom of approximately 0.23 mm and a wall thickness near its free end of approximately 0.25-0.26 mm. This difference in wall thickness is ironed, particularly in the free end zone, using the operation schematically illustrated in figures 10 and 11.

Figure 10A shows the preform 33, which is placed on tool parts 35 and 36. A tool fine drawing or stretching tool 38 is pressed into the preform 33 (see Figure 10B), thereby ironing the thickness of the body at an average value of 0.22 mm. After the withdrawal of the stretching tool 38 the edge 31 of the preform 39 subjected to deep drawing and fine drawing is removed by cutting using a rotary cutting device 40. The preform embedded and trimmed is released afterwards and shown in the figure 12.

Figures 13A-13D show the First subsequent neck formation operation. This formation of neck is carried out by means of the denominated formation of collar with chuck The neck forming apparatus 42, which is shown in figure 13A, comprises a clamping tool 43 which holds the preform 41. The clamp is connected to a plate base 44 carrying two levers 45. The short arm 46 of the lever 45 cooperates with a post 47 placed on a table 54, and the arm longer 48 cooperates with a post 49 supported by a fixed table 50. The support 44 is lowered towards a table 54 carrying a mandrel 51 sliding on a support 53, which cooperates with the clamp 43 in which the preform 41 is held. The shorter arms 46 make contact with posts 47 and arms plus Sargos 48 make contact with the posts 49 (see figure 13B). The additional movement towards below the support 44 according to arrow 52 causes a movement towards below the mandrel 51 in relation to its support 53 in which the mandrel 51 is arranged slider while it is inserted into the preform 41.

As shown in Figure 13C the movement down following the arrow 52 of the support 44 results in a leverage of both levers 45. This results in a setback of the mandrel 51 in its sliding support bracket 53, while posts 47 on table 54 are pressed further down by the levers 45 using the short arms, since the arms long lean on fixed posts 49. The final stage is shown in figure 13D. Here it is shown that mandrel 51 is held in he and presses against the sliding support support 53 the area of free end 55 of the preform 41 held in the clip 43. This situation is shown in more detail in figure 14A and figure 14B. The preform 41 is embedded following the arrow 56 with the mandrel 51 inserted at the free end, in the sliding support bracket 53 or shaping tool. Indeed, the mandrel 51 embute, following arrow 57, the free end zone 55 through the narrow opening 58 to form the neck-shaped part. The neck formation is done in this way while the part to the one that is going to form a neck leans inwards on a mandrel 51 and is embedded (instead of being pushed) through the neck training tool. Accordingly the force axial down is low. The formation of the neck results in a slight increase in material thickness of the order of 4%.

Progressively, the diameter of the area of neck-shaped free end can be reduced in stages from approximately a diameter of 20 mm to a diameter of approximately 15 mm These neck training operations or stage reductions can be carried out in 2-10 stages, in this case in 6 stages. Each stage neck training needs tools adapted to the clamp, neck forming ring and mandrel.

The preform 59 with collar is subjected after a cutting operation in which using a rotary cutting device 60 the free end is trimmed giving place a sharp edge 61 in the neck portion 62 of the preform 63 (see figures 15 and 16).

Figures 17-19 show the beading operation for the open end of the preform of container. Figures 17 and 18 show the conformation of the previous flange.

Figure 17 shows a preform that is inserted into a support 65 of the first beading apparatus 66.

The end zone 67 of the preform 64 is placed on a support 68 and is brought into contact with a beading tool 69 which is rotatably supported on bearings 70 on a support 71.

As shown in Figure 18A, support 65 turn according to arrow 72 and scroll down according to the arrow 73. In this way the free edge 74 of the end zone 67 makes contact with the beading tool 69 on its surface flange 75. This free end 74 bends toward the outside following arrow 75 and due to the downward movement following arrow 73, a previous flange 76 is formed until the free end touches the outer surface 77 of the end zone free 67. Consequently, preform 78 is formed.

As shown in figure 19 this preform 78 provided with the previous flange 76 undergoes a second operation of beading in the beading apparatus 79. The apparatus of beading flanged 79 comprises a support 80 into which the preform 78. Subsequently, during rotation following the arrow 81 and due to the downward movement following arrow 82, the previous flange is pushed against the flange surface 83 of a beading tool 84 thereby providing the area of end 85, which already had the previous flange 76, in addition to a flange additional elongated This elongated flange moves radially outward, but it is pressed inwards and so radial following a conformation function 86, Finally, as shown in figure 19C elongated flange 87 is formed still comprising the previous flange 76. Due to this process Manufacturing, flange dimensions and quality is substantially constant. Released from Figure 19C it It has the steel container 88 as shown in Figure 1A.

Figures 20-27 show a alternative for fine drawing and free end trimming of the embedded container preform as shown in the Figures 10 and 11.

A preform 89 mounted on a punch 90 is pass by following arrow 91 through the tools of fine drawing 92 and 93. During passage the body 94 of the preform 89 undergoes fine drawing.

The preform also passes through the rings separators 95 and 96.

Figure 21, and in particular detail XXVI illustrated in figure 26, shows the passage of the punch 90 through of tool 93. An annular opening 95 decreases so progressive as a result of a fine drawing of the body 94.

As shown in Figure 22, and in particular in detail XXVII illustrated in Figure 27, punch 90 has a punch edge 96 of larger diameter so that the space between tool 93 and punch 90 is reduced to approximately 0.05 mm This results in a cutout of an end part 97 in ring shape, which remains upstream of the tool 93 arranged slider in the punch and its piston 98 (see figure 22).

The punch 90 moves further following the arrow 99 until the bottom 100 of the preform 89 makes contact in a tool 101 for shaping the shape of concave bottom (see figure 23). Subsequently, punch 90 is removed following arrow 103. However, a separator 104 of preforms are held before the free end 105 of preform 89, such that preform 89 separates from punch 90 while that the punch 90 is removed through the ring 93 according to the arrow 103 (see figure 24). In this way the preform 89 is released. In a manner a trimmed ring separator 106 keeps facing to trimmer 106 the cut ring ring 97. When the punch has been removed beyond the clipping separator 106, then the trimmed ring 97 is released and picked up.

Figure 28 shows an alternative for trimming operation as described in figures 15 and 16. The preform 107 is trimmed at its free end 108 with neck in one final operation of neck formation.

The left cross-section of the Figure 28 shows the preform 107 resting on a support 109. This support 109 moves in relation to a ring 110 of neck formation and a mandrel 111. The inside diameter of the free end 108 with collar is such that mandrel 111 could be displaced within preform 107.

During relative subsequent displacement between the support 109, the neck forming ring 110 and the mandrel 111 (see also figures 14A and 14B figure) the end Free 108 with neck shape resting on mandrel 111 is embedded through neck opening 112.

As shown in greater detail in the figure 29, the mandrel 111 is provided with a step 113, which is corresponds to a similar step 114 in the opening 112 of the ring 110 neck formation. This results in a pinch of a part 115 of the free end 108 which cuts the preform 107.

Thus, according to this embodiment the trimming of the preform and the final neck formation operation could be carried out in the same and single unit and in the same and unique operation.

According to the various embodiments, produces a steel container that has an open end with flange that meets the objectives in relation to the stability of dimensions, ease of production and sufficient strength to that a tight closure can be formed by gripping a closure or a dispensing unit In addition, the steel may be coated in a or both sides in order to provide the steel with improved properties, such as corrosion properties or other aesthetic properties. Still, a stratified steel sheet can be used coated on one or both sides and these coatings are still  present in the steel container produced.

In addition, it should be noted that the various operations used in the container shaping method of steel according to the invention and the various units used in the apparatus for forming a container of steel according to the invention can be implemented in a single and same apparatus in which the preforms are circulated through the different units to be subjected to the different operations. On the other hand the same steel container can be manufactured using various devices to perform operations as defined in the claims herein patent.

Claims (19)

1. Method for forming a container of steel (1, 9), such as a pressure vessel, which has a open end (6) with flange, comprising the steps of:

i)

provide a steel cup (eleven);

ii)

subject the cup to deep drawing steel (11) to a preformed embedded container (12);

iii)

subject to fine drawing the body (2, 94) of the embedded container preform (12); characterized in that the free end (15) of the embedded container preform (13) is cut by tightening; Y

iv)

beading an open end of the preform of embedded and trimmed container (14) by means of the conformation of a previous flange (16, 18, 76) and through the flanged from the previous flange (16, 18, 76) to a flange elongated (4, 19, 87).

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2. Method according to claim 1, wherein the steel cup (11) is provided by forming from of a steel sheet (10), preferably by drawing. 3. Method according to claim 1 or 2, in the that the deep drawing stage ii) comprises several stages of deep drawing, preferably 2-6 stages of deep drawing, such as three stages of drawing deep 4. Method according to any of the claims 1-3, wherein the preform of container (13) is provided with a concave bottom (8, 18) formed during or after the deep drawing stage ii). 5. Method according to any of the claims 1-4, wherein an end zone Free (32) of the embedded container preform is formed as a neck, preferably in several stages of neck formation, such as 2-10 stages of neck formation. 6. Method according to claim 5, wherein at least one stage of neck formation comprises formation Neck with mandrel. 7. Method according to claim 5 or 6, in the that the free end (3) with neck is trimmed by tightening. 8. Method according to any of the claims 1-7, wherein the steel is coated on at least one face with a coating. 9. Method according to claim 8, wherein at least the free end zone (32) to which it will be given neck shape, undergoes heat treatment such as 100-400 ° C, preferably 150-350 ° C, such as 200-300 ° C. 10. Method according to claim 9, wherein The heat treatment comprises induction heating. 11. Apparatus for the formation of a container of steel (5), such as a pressure vessel (5), which understands:

i)

a unit for deep drawing of a steel cup (11) in a preform (12) of embedded container;

ii)

a unit for fine drawing of the body (6) of the embedded container preform (13, 33); characterized in that the apparatus further comprises a trimming unit for squeezing the free end (15) of the inlay container preform (13, 33); Y

iii)

a unit for the beading of an open end of the preform of embedded container (14), said beading unit comprises a pre-flange conformation subunit and a subunit of conformation of elongated flange.

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12. Apparatus according to claim 11, which It comprises a unit for shaping the steel cup a Starting from the steel plate. 13. Apparatus according to claim 11 or 12, in which the deep drawing unit comprises several subunits  deep drawing, preferably 2-6 deep drawing subunits, such as three subunits of deep drawing 14. Device according to any of the claims 11-13, comprising a unit for the formation of a concave bottom (8) in the preform of container (30). 15. Device according to any of the claims 11-14, comprising a unit (42) neck formation to form a neck in an area of free end of the embedded container preform, comprising preferably several neck forming subunits, such as 2-10 subunits of neck formation. 16. Apparatus according to claim 15, in the that the neck formation unit comprises a subunit (51) Neck formation with mandrel. 17. Apparatus according to claim 15 or 16, which comprises a trimming unit by tightening to trim by tighten the free end with the shape of a neck. 18. Apparatus according to any of the claims 11-17, comprising a unit of heating to heat at least the free end zone (32) which will be shaped like a neck. 19. Apparatus according to claim 18, in the that the heating unit comprises a heating unit  inductively.